1. Field of the Invention
Exemplary embodiments of the present invention relate to a method and apparatus for enhancing quality of a depth image; and, more particularly, to a method and apparatus for further enhancing quality of a depth image which has already been acquired.
2. Description of Related Art
As interest in three-dimensional (3D) images has increased in recent years, much research has been conducted on 3D image technologies. In order to render a 3D image, it is necessary to acquire 3D information or depth information of an object or scene.
Unlike a general video image, a depth image refers to an image which includes depth information of an object or scene from a camera. The depth information is represented with a value of 0 to 255. The value of 0 represents that an object or scene is located farthest from a camera, and the value of 255 represents that an object or scene is located closest to a camera.
A depth image may be acquired by two methods. A first method is an active method which acquires a depth image by using an active 3D information acquisition apparatus. A second method is a passive method which acquires a depth image by using a correlation between images acquired from a multi-view camera at the same time. A representative example of the passive method is a stereo matching.
A representative example of the active method is a Time-Of-Flight (TOF) method. In the case of the TOF method, a non-visible light is irradiated on an object, and the time taken for the irradiated light to return back from the object is measured. Then, a depth image is created by calculating a distance from a camera to the object by using the measured time. Although the TOF method can create a depth image in real time, it is difficult to acquire a high-quality depth image due to irregular reflection or noise which occurs in bright environments.
In the case of the passive method, the correlation of the respective points of view is calculated from multi-view images acquired through a multi-view camera by using software, and a depth value is obtained by calculating a disparity value between the points of view through the calculated correlation. Since the passive method calculates the depth value by using only several limited components, it is likely to acquire depth information different from the real depth information.